I purchased an Epiphone Valve Junior guitar amplifier with the intent to convert it to a cheap, general use, EL84 SE monoblock audio amplifier. I found a schematic called the RH 84 SE(thanks RH Design) and used it to modify the Valve Jr. The result works and sounds much better than it ever has for HiFi use. It uses line-level inputs nicely and seems to have plenty of gain. All good so far.

This is not my first amp project BUT I'm still very green with tube technology and I lack experience with these types of amplifiers. If you are interested, I invite you to stop by my blog and read up on the project. I have pictures and schematics that I simply could not list here.

Here is the final schematic with my edits. If you see anything that is wrong or could be better (besides the cheap Hammond output transformer - I know) please let me know. I'm counting on more experienced amp techs to help guide me to getting this amp to sound nice(er) and not overdrive the tubes for long service life. The output transformer will be replaced at some point in the future.

please excuse me, i have a small question- if i was to make my own circuit similar to that of the VJ, would it be possible to use i without an output transformer with say a 600 om resistor in series with an 8 ohm speaker grounded at the other end? im building a small guitar amp (about 3 to 8 watts) out of bis i have, using an el84- thanks in advance

please excuse me, i have a small question- if i was to make my own circuit similar to that of the VJ, would it be possible to use i without an output transformer with say a 600 om resistor in series with an 8 ohm speaker grounded at the other end? im building a small guitar amp (about 3 to 8 watts) out of bis i have, using an el84- thanks in advance

You mean without an output transformer? In short, no. EL84 is high impedance, and wants to see around 5000 Ohms connected to it. So you could in theory have a 4K8 or 5K6 10 Watt resistor connected between HT and the anode, and take the output through a capacitor connected between anode and loudspeaker, but a lot of power will be dissipated on the resistor, and your output will be low.